Vehicle bumpers in the related art including a bumper beam, a bumper face covering the front surface of the bumper beam, and an energy-absorbing member interposed therebetween, for reducing the degree of injury to a pedestrian's leg are proposed in Japanese Patent Laid-Open Publication Nos. 2004-155313 and HEI-11-208389, for example. The vehicle bumper in 2004-155313 will be described with reference to FIGS. 11A and 11B; the vehicle bumper in HEI-11-208389 will be described with reference to FIGS. 12A and 12B.
FIG. 11A shows a bumper structure 100 with an energy-absorbing member 104 including a plurality of support walls 103 interposed between a bumper beam 101 and a bumper face 102, in a state of collision with a pedestrian's leg 105.
When the bumper face 102 strikes a portion 106 below the knee, a thigh 107 starts to incline in the direction of arrow a. As shown in FIG. 11B, the thigh 107 and the knee 108 are displaced toward the vehicle. At that time, the energy-absorbing member 104 is deformed more greatly at an upper portion thereof than at a lower portion. That is, the deformation according to the displacement of the parts of the leg 105 reduces the degree of injury to the leg 105.
The energy-absorbing member 104, however, has low energy-absorption performance because it consists of the support walls 103 and has a limited vertical length. To increase the energy-absorption performance, it is necessary to enlarge the energy-absorbing member 104, that is, to extend it vertically and longitudinally (from side to side in the figure). This will cause a new problem of adversely affecting the appearance of the vehicle and the engine cooling performance.
An energy-absorbing member 110 shown in FIG. 12A consists of a lower block and an upper block. The upper block provided at the height of a leg consists of separate bodies 111. A plurality of slits 112 are formed between the separate bodies 111 in a vertical direction.
The provision of the slits 112 between the separate bodies 111 constituting the upper block allows the energy-absorbing member 110 to be made compact. However, absorbed energy differs greatly depending on the place of collision on the separate bodies 111.
The reason why absorbed energy differs depending on the place of collision will be described below.
If a leg 113 collides with a separate body 111 as shown in FIG. 12B, the leg 113 does not come into any slit 112. Consequently, the separate body 111 is compressively deformed without flexibly deformed laterally. This prevents some portions from absorbing the load of the leg 113, making it impossible to sufficiently reduce the degree of injury to the leg 113, depending on the place of collision.
The bumper structure shown in FIGS. 12A and 12B varies in the amount of energy absorption depending on collision areas, and leaves room for improvement as a bumper structure intended for energy absorption. That is, there is demand for a vehicle bumper which is compact and can sufficiently reduce the degree of injury to a pedestrian's leg.